This impressive amethyst-lined geode shows hundreds of glittering crystals. Brazil contains some of the deepest purple amethyst and largest geodes ever found. When tall and thin, these large amethystlined geodes are often called ‘cathedrals’ because they resemble a cathedral arch.
Amethyst geode. Sao Gabriel, Rio Grande do Sul, Brazil
85 x 85 x 30 cm.
The geological origin of these geodes is from cavities in volcanic rocks. They are mined from massive lava flows in the Parana Continental Flood Basalt Province, which poured out about 800,000 cubic km of lava over 11 million years.
This specimen, weighing 114 kg, was sourced by Albert Chapman at the Tucson Gem and Mineral Show in the USA in 1984 from the Aurora Mining Company. It was purchased especially for the Planet of Minerals exhibition at the Australian Museum, which opened in 1986.
Quartz (amethyst) on chalcedony
Uruguay. 11.5 x 10 x 13.1 cm.. D.50289. Albert Chapman Collection.
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